This invention provides a work platform for coiled-tubing downhole operations apparatus and method, for safe, efficient, and relatively inexpensive extended access to the elevated top of the section of riser pipe necessary for the use of coiled tubing for downhole operations, such as drilling, production, intervention, logging, work-over, and fracturing the reservoir.
The increasing use of coiled tubing, rather than using segmented drill pipe, provides advantages associated with not having to stop and assemble and disassemble drill pipe, and not requiring use of a tall derrick for drilling and for subsequent downhole operations. Coiled-tubing operations make use of a bottom-hole assembly (or “BHA”) for all tools, including drilling tools, and therefore do not rotate the tubing. There is thus no need for a rotary table. Operations using coiled tubing can be run in a balanced, over-balanced, or under-balanced state. Running under-balanced helps prevent the forcing of fluids into the underground formation, therefore killing all or part of the well.
Coiled-tubing operations require a length of riser pipe above the well-head and blowout preventer, in order to straighten the tubing. It is normal to have three ten-foot sections of riser pipe, or thirty feet, above the blowout preventer. These sections place the injector and access to the entry point of the tubing between approximately thirty to forty feet above the ground for onshore operations. This elevated equipment has to be inspected and serviced often, and so a safe and stable work platform must be located at the elevated entry point of the riser shaft.
Although an expensive derrick is not needed for the assembly and disassembly of drill pipe, a derrick might be used to provide the elevated work platform. Such a derrick would be expensive, and perhaps prohibitively so for certain operations. Alternatively, scaffolding might be erected to provide a work platform. But such scaffolding is complex, time-consuming to put in place, is subject to being thrown out of adjustment relative to the top of the riser pipe, is difficult to climb, and does not provide an optimum work platform.
There is a thus need for a work platform for coiled-tubing downhole operations that is safe, efficient, and inexpensive relative to a derrick or scaffolding, and further is fixed in place relative to the top of the riser pipe, and may be left in place for extended periods of time.